1. Field
The present disclosure relates generally to sensors and, in particular, to a method and apparatus for powering a sensor. Still more particularly, the present disclosure relates to a method and apparatus for powering a sensor with integrated electronics using a constant current power source.
2. Background
The measurement of physical quantities is often performed to determine and understand the behavior of physical phenomena. For example, the measurement of noise and the sources or causes of noise is often performed to understand the physics behind the generation of noise. For example, a measurement may be performed to identify where the noise is coming from.
This type of analysis may be performed in the testing of devices. For example, noise data may be collected for an aircraft engine, such as a jet engine. The noise data collected may be analyzed to determine what components within and exterior to the jet engine contribute to the noise. These different components may also be referred to as component noise sources.
Different structures or components in a jet engine or in the jet exhaust generated by a jet engine may contribute different noises at different frequencies. For example, different surfaces within ducts and inlets of a jet engine may contribute noise during the operation of the jet engine. For example, the high speed exhaust flow of a jet engine may contribute noise during the operation of the engine.
Surfaces may be treated with various compounds or components in an effort to reduce noise. With this type of example, the jet engine may be tested with the different types of surfaces to determine whether a noise contribution from those surfaces is reduced with the different treatments.
Currently, arrays of microphones may be used to collect noise data. This noise data may be processed to produce a “picture” of where the noise is coming from, and to determine the intensity of the radiated noise. In obtaining this data, sound sensor units, such as microphones, may be placed at different locations. With current array designs, hundreds or thousands of array locations are needed to cover all the sound propagation paths formed by connecting hundreds of candidate noise source locations to dozens of measurement points of interest.
Each of the microphones in the array is part of a channel to collect data from different noise sources. Each channel within an array may be around $3,000.00 or more. Further, existing microphones and equipment for a channel may have constraints with respect to installation and/or flexibility because of the physical shape and size of the different components. Typically, piezoresistive sensors may be powered using an external direct current constant voltage source.
Signal conditioning electronics also may be located external to and connected to the sensor. These types of configurations require multi-conductor cables to provide connections for excitation, signal transfer, and shielding. These multi-conductor cables may have around four to five wires.
With the complexity and cost of these types of channels, a large initial cost is present to obtain an array of microphones.